Notes:
1. Even if your sample is a solid, do not use vials with paper-lined caps.
We often put samples in a solvent. Methanol and acetonitrile, for example,
extract astonishing arrays of ions from non-PTFE-lined caps.
2. If
your research group has a person trained and checked out to operate
the matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF)
instrument, it may be quicker to have that person run your sample than to
wait
for Instrument Center personnel to run it.
3.
Ionization methods available:
ESI and MALDI work really
well with compounds with functional groups that can be
protonated or deprotonated in water and with compounds that form complexes
with
positive ions such as Na+, K+, Ag+, and Cu+2. Generally, compounds do not
protonate/deprotonate and form metal ion complexes in an EI source, and generally
ESI and MALDI do not produce lots of fragment ions like EI does. Remember,
mass spectrometry detectors recognize positive or negative ions. They do not register
neutrals. So any suggestions for how to ionize your neutrals will be appreciated. Please place your suggestions on your Request Form.
If you have any questions
on how mass spectrometry samples are handled,
please see me. If you are interested in being trained to operate the MALDI-TOF
MS
or the LCMS or the GCMS, please let me know.
M. M. Vestling, Rooms 2142 and 2134 or vestling@chem.wisc.edu